Although 20 years ago, one treatment fits all was the approach taken which led to formidable “blockbuster” drugs. Today with the sequencing of the human genome and advances in molecular profiling technologies, approaches to drug development are taking a more stratified or personalized approach. These advances increasingly allow for classification of individuals into subpopulations that are at risk of a specific disease, respond to a specific treatment, don't respond to a specific treatment or are at high risk of an adverse event when treated. As such genetic tests can be used to inform diagnosis, prognosis and treatment selection. Numerous studies have shown a relationship between genotype and response to pharmaceutical therapies. This approach has been widely embraced over the past years, particularly in oncology where numerous personalized medicine approaches have been successfully developed and have provided major improvement in clinical outcomes.
In cardiovascular disorders the stratification of the population by genotype for a specific therapeutic intervention has been limited. One of the objectives of the present invention is to demonstrate that the population suffering from cardiovascular disorders might behave differently and consequently may respond differently to a specific treatment. Lowing LDL is an important therapeutic strategy in the management of cardiovascular disease. Indeed statin drugs, which lower LDL, such as Crestor, Lipitor, Pravachol, and Zocar are widely used and among the most prescribed drugs. For some time it has also been generally accepted that increasing HDL could also be therapeutic in cardiovascular disease. Several HDL-raising drugs have been developed including: niacin and CETP inhibitors such as torcetrapib, anacetrapib, evacetrapib and dalcetrapib.
Cholesterylester transfer protein (CETP) also called plasma lipid transfer protein is a hydrophobic glycoprotein that is synthesized in several tissues but mainly in the liver. CETP promotes bidirectional transfer of cholesteryl esters and triglyceride between all plasma lipoprotein particles. The first evidence of the effect of CETP activity on plasma lipoproteins was provided by observations in people with genetic deficiencies of CETP. The first CETP mutation was identified in Japan in 1989 as a cause of markedly elevated HDL-C. Ten mutations associated with CETP deficiency have since been identified in Asians and one in Caucasians. It was found in Japan that 57% of subjects with levels of HDL-C >100 mg/dL have mutations of the CETP gene. In addition, 37% of Japanese with levels HDL-C between 75-100 mg/dL have mutations of the CETP gene. Subsequently, studies of animals treated with an anti-CETP antibody showed that CETP inhibition resulted in a substantial increase in the concentration of HDL-C. Consistent with these observations in CETP deficient patients and rabbits treated with an anti-CETP antibody, it has since been found that treatment of humans with CETP inhibitor drugs increases the concentration of HDL cholesterol and apoA-I (the major apolipoprotein in HDLs). Numerous epidemiologic studies have correlated the effects of variations in CETP activity with coronary heart disease risk including studies of human mutations (Hirano, K. I. Yamishita, S. and MatsuzawaY. (2000) Curr. Opin. Lipido. 11(4), 389-396).
Atherosclerosis and its clinical consequences, including coronary heart disease (CHD), stroke and peripheral vascular disease represents an enormous burden on health care systems internationally. Drugs that inhibit CETP (CETP inhibitors) have been under development for some time with the expectation that they will be useful for treating or preventing atherosclerosis. A number of classes of CETP inhibitor drugs have been shown to increase HDL, decrease LDL in humans and to have therapeutic effects for treating atherosclerosis and cardiovascular disease including dalcetrapib, torcetrapib, anacetrapib, evacetrapib, BAY 60-5521 and others (Table 1).
TABLE 1Overview of Lead CETP Inhibitor Drugs and Clinical StatusStructureCompoundClinical phaseTorcetrapibPhase III discontinued in 2006 AnacetrapibPhase III DalcetrapibPhase III trial halted May 2012 BAY 60-5521Phase I
However there is evidence that these drugs may not be safe and effective in all patients. The clinical trial for torcetrapib was terminated in Phase III due to incidence of mortality in patient to whom torcetrapib and atorvastatin were administered concomitantly compared to patients treated with atorvastatin alone. The clinical trial for dalcetrapib was also halted in Phase III in this case due to a lack of efficacy relative to statins alone. Additional CETP inhibitors are still being pursued in clinical trials and earlier stage development. In general treatment strategies using CETP inhibitors that provide better efficacy, reduced off-target effects would be clinically beneficial. There is a need for biomarkers, methods and approaches for predicting response to CETP inhibitors and accessing risk of adverse events associated with administration of CETP inhibitors.
CETP inhibitors are useful for the treatment and/or prophylaxis of atherosclerosis, peripheral vascular disease, dyslipidemia, hyperbetalipoproteinemia, hypoalphalipoproteinemia, hypercholesterolemia, hypertriglyceridemia, familial hypercholesterolemia, cardiovascular disorders, angina, ischemia, cardiac ischemia, stroke, myocardial infarction, reperfusion injury, angioplastic restenosis, hypertension, and vascular complications of diabetes, obesity or endotoxemia.
Clinical trials have shown that patient response to treatment with pharmaceuticals is often heterogeneous. There a pressing need to improve drug development, clinical development and the therapeutic impact of drugs for individuals or sub-populations of patients. Single nucleotide polymorphisms (SNPs) can be used to identify patients most suited to therapy with particular pharmaceutical agents (this is often termed “pharmacogenomics”). Similarly, SNPs can be used to exclude patients from certain treatment due to the patient's increased likelihood of developing toxic side effects or their likelihood of not responding to the treatment. Pharmacogenomics can also be used in pharmaceutical research to assist the drug development and selection process. Linder et al, Clinical Chemistry 43:254 (1997); Marshall, Nature Biotechnology 15: 1249 (1997); International Patent Application WO 97/40462, Spectra Biomedical; and Schafer et al, Nature Biotechnology 16:3 (1998).
The dalcetrapib mortality and morbidity trial (dal-OUTCOMES) was a double-blind, randomized, placebo-controlled, parallel group, multi-centre study in stable CHD patients recently hospitalized for acute coronary syndrome (ACS). The study was conducted to test the hypothesis that CETP inhibition will reduce the risk of recurrent cardiovascular events in patients with recent ACS by raising levels of HDL-C through CETP inhibition. Eligible patients entered a single-blind placebo run-in period of approximately 4 to 6 weeks to allow for patients to stabilize and for completion of planned revascularization procedures. At the end of the run-in period, eligible patients in stable condition were randomized in a 1:1 ratio to 600 mg of dalcetrapib or placebo on top of evidence-based medical care for ACS. Dalcetrapib is an inhibitor of cholesterol-ester transfer protein (CETP). It has been shown to induce dose-related decreases in CETP activity and increases in HDL-C levels in several animal species and in humans. Decreasing CETP activity, through different approaches, has demonstrated anti-atherosclerotic effects in several animal models. The trial was interrupted in May 2012 by the DSMB on grounds of futility. The dal-OUTCOMES study resulted in unexpected observations related to cardiovascular disease progression. Despite a marked increase in HDL-c, patients on treatment did not show a significant reduction in cardiovascular events and the study was terminated.
Following the termination of dal-OUTCOMES study, it was hypothesized that a subgroup of the patients under study were responding differently to dalcetrapib and that dalcetrapib could be having a significant therapeutic effect in a sub-population of patients. A pharmacogenomic study of the dal-OUTCOMES study population was conducted to study the inter-individual variation in dalcetrapib response and to identify genetic markers for predicting therapeutic response to dalcetrapib, or other CETP inhibitors, for patient stratification and for treatment selection.